1. Field of the Invention
The present invention relates to carnitine-containing peptides which are capable of delivering exogenous carnitine across cell membranes and intestinal mucosae to provide carnitine to a mammal.
2. Description of the Background
Carnitine is a naturally occurring amino acid required for mitochondrial oxidation of long-chain fatty acids. It is a betaine derivative found in skeletal muscle and liver, and acts as a carrier of fatty acids across the mitochondrial membrane into the mitochondrial matrix, where the fatty acids combine with coenzyme A (CoA) to form acyl CoA. Carnitine has the formula: ##STR1##
Juvenile humans possess a carnitine transport system in the intestine, however, it appears that this active transport system becomes less active in adulthood, resulting in low carrier-mediated absorption of carnitine. Passive diffusion is the dominant method of crossing the intestinal barrier for carnitine, but is not efficient because carnitine compounds are quite polar. Consequently, adult humans are largely unable to assimilate large amounts of carnitine. Carnitine deficiency is associated with a number of disorders, one of which is a slowly progressive proximal polymyopathy with lipid storage in muscle fibers. Unfortunately, without the carnitine transport system, adult humans are unable to assimilate exogenous carnitine across cell membranes and intestinal mucosae to remedy the deficiency.
Thus, a need exists for a means by which carnitine may be effectively transported across cell membranes and intestinal mucosae in mammals, particularly in humans.